The global objective of this research application is to provide new insights into the mechanism by which the membrane protein prestin confers electromotile properties to outer hair cells (OHCs). It has been proposed that OHC electromotility functions as the cochlear amplifier in mammalian hearing, and that damage to OHCs results in distinct and dramatic hearing loss. This study will examine the behavior of prestin in the plasma membrane, specifically focusing on the lateral mobility or diffusion of the protein in several cellular systems under various environmental conditions. Mobility studies will be conducted using the powerful and established technique of fluorescence recovery after photobleaching (FRAP). Individual experiments will focus on how lateral diffusion is affected by membrane cholesterol concentration, small anion concentrations, salicylate and chlorpromazine, as well as membrane tension experiments. We hypothesize these perturbations produce alterations in plasma membrane properties, which influence the behavior of prestin. The results of these studies will provide valuable information about how the plasma membrane environment affects and interacts with prestin and will shed light on the action of ototoxic drugs.